Photographic developer.



UNTTnn STATES PATENT OFFICE.

ARTHUR EICHENGRIIN, OF ELBERFELD, GERMANY, ASSIGNOR TO FARBEN- FABRIKEN OF ELBERFELD (10., OF NEWV YORK, N. Y., A CORPORATION OF NEW YORK.

PHOTOGRAPHIC DEVELOPER.

SPECIFICATION forming part of Letters Patent No. 707,403, dated August 19, 1902. ,6 Original application filed December 17,1901, Serial No. 86,805. Divided and this application filed May 23, 1902. Serial To all whom, it may concern:

Be it known that I, ARTHUR EIcHnNeRiiN, doctor of philosophy, chemist, residing at Elberfeld, Germany, (assignor to the FAR- BENFABRIKEN on ELBERFELD Go., of New York,) have invented a certain new and use ful Improvement in Photographic Developers, of which the following is a specification.

The present application is a divisional ap- IO plication from my original application, Serial No. 86,305, filed December 17, 1901.

As is known, neutral and acid sulfites of alkalies are employed in photography as admixtures to photographic developing-baths in order to prevent an oxidation of the developer which is employed. However, the use of sulfites has many disadvantages, inasmuch as their solutions cannot be kept for any length of time, and the sulfites are decomposed by the action of the air. I have now found that these disadvantages in developing photographic pictures can be obviated byemployin g instead of the above-mentioned sulfites the addition compounds obtained from ketones 2 5 and bisnlfites, especially the compounds which are prepared from acetone and the potassium or sodium bisulfites, the so-called acetone alkali bisulfites having the following general formula M meaning an alkali metal, such as potassium or sodium. These addition compounds (No specimens.)

have the great advantage that they are readily soluble in water and that even their concentrated solutions can be kept for a long time in a well-corked bottle without decomposing. On adding alkalies to thedeveloping-bath containing acetone alkali bisulfites the latter yield acetone, which, as is known, has a very good influence on the developing process. Small quantities of the acetone alkali bisulfites SllffiCG to render the developing-baths stable. For instance, the following formula may be employed with good results: one'part of pyrogallol, 2.5 parts of acetone alkali bi= sulfite, six parts of potassium carbonate, and one hundred parts of water.

The developing agent prepared as above will keep for a very long time Without decomposing and can be used for all kinds of sensitized materials, such as glass, films, bromidpapers, 820.

Having thus described my invention and in what manner the same is to be performed, what I claim as new, and desire to secure by Letters Patent, is

The herein-described new developing agent containing a reducing agent, an alkaline agent and acetone alkali bisulfites, substantially as hereinbefore described.

In testimony whereof I have signed my name in the presence of two subscribing witnesses.

ARTHUR EICHENGRUN. Witnesses:

O'rro Konre, J. A. RITTE'RSHAUS. 

